42" Long Heavy Duty Floating Shelf Hardware - for a 44" to 47" Shelf - Manufactured in USA Hidden shelf hardware, engineered to support shelves that are 2" - 2 1/4" thick, and from 7" to 14" deep. The original patented bracket Simple to install on masonry, sheetrock, plaster, and paneled walls This hardware will support a maximum distributed load up to 135 lbs., when installed correctly Screw holes are set 1" OC from each end and continue 4" OC down the length of the hardware. Countersunk screw holes are 3/16" OD A set screw hole can be drilled in the outside rods to screw the shelf to your hardware. You can also glue the shelf onto the hardware with silicone. Both are equally effective, glue is the easiest method